For example, the Japanese patent No. 63-188433 (hereinafter referred to as ‘the Invention A’) and No. 10-85878 (applied by the applicant of the current patent application, and hereinafter referred to as ‘the Invention B’) are examples of the prior arts, which keep the entire length of insert tubes being enlarged, at an almost same level, even after the enlargement.
That is, as shown in FIG. 12(a), as a method of fixing a hairpin tube 7 at a heat radiating fin by inserting a tube-enlarging mandrel 2 into the opening 7b of said hairpin tube 7 in a heat exchanger 5, in a configuration where multiple hairpin tubes 7 are inserted into multiple heat radiating fins 6 which are overlaid and separated by a prescribed space isolation, ‘the Invention A’ provides a method wherein                the hairpin part 7c of said hairpin tube 7 is fixed by a hook body 10 which is not movable toward said opening 7b;         then the tube 7 is enlarged at the side of the opening 7b, rather than the side of the heat radiating fin 6, by inserting the tube-enlarging mandrel 2 from the opening 7b of the tube 7, and then the enlargement portion 7d is fixed in the through hole 9 of the clamp 8 which is not movable toward the said hairpin part 7c;         then, the tube-enlarging mandrel 2 is inserted into the hairpin tube 7, in the state where the hairpin tube 7 is fixed by the clamp not to move toward the hairpin part 7 and the hairpin tube 7 is fixed by the hook body 10 not to move toward the opening 7b.         
According to the method above, after the side of the opening 7b of the hairpin tube 7, rather than the side of the heat radiating fin 6, is fixed in the through hole 9 of the clamp 8 at the side of the opening 7b not to move toward the hairpin part 7c, the hairpin tube 7 tends to shrink during the enlargement process of inserting the tube-enlarging mandrel 2. However, since the hairpin part 7c is also fixed by the hook body 10, shrinkage of the hairpin tube 7 is prevented and absorbed by reducing the thickness in the hairpin tube 7. As a result, shrinkage in the entire length of tubes is kept at a minimum even after the enlargement.
However, the heat exchanger production method explained above has problems as detailed below.
That is, in the method above, as shown in FIG. 12(b), since the opening 7b of the hairpin tube 7 is fixed in the through hole 9 of the clamp 8, if hairpin tubes are inserted in a zigzag pattern in multiple columns such as columns of 3, 4, or etc., there exists a problem that hairpin tubes 7 sitting at the interior side in the heat exchanger cannot be fixed by the clamp 8.
On the other hand, as shown in (c) in the same figure, the problem above can be resolved, by mechanically varying the diameter of the through hole 9 of the clamp 8, by an aperture-like tool operating like an aperture in a camera. However, if the space between each of hairpin tubes 7 is fully taken up with complex components, or if said space is smaller than the gap between said aperture-like tools, there exists a space problem for setting up said aperture-like tools, and thus the limiting factor stated above still develops.
Also, if the diameter of the hairpin tube being enlarged in the heat exchanger 5 is changed according to the spec of the heat exchanger 5, the through holes 9 of the clamp 8 can no longer firmly fix the side of the opening 7b of the hairpin tube 7. Also, other various similar problems develop.
Thus, to resolve all of the problems stated above, the applicant of this application applied ‘the Invention B’ for the patent registration. According to ‘the invention B’, as shown in FIG. 1, in a heat exchanger production apparatus 1 configured with the main body 1a installed on the base platform 1b, 1c is the component-loading platform of the heat exchanger 5, which is vertically installed on said base platform 1b. Inside said heat exchanger 5, a plurality of hairpin tubes 7 with prescribed lengths are inserted in a row (not shown in the figure) into multiple heat radiating fins 6 along the surface of the component-loading platform 1c. Also, above said component-loading platform 1c, a pressing-plate 11 is installed to elevate in order to press and fix said heat exchanger 5 between the component-loading platform 1c and the pressing-plate 11.
2 represents the tube-enlarging mandrel which is installed for moving back and forth on said main body 1a, keeping its horizontal status. As shown in FIGS. 2(a) and (b), the tube-enlarging mandrel 2 is connected from its exterior to the tube-grasping body 3 to enable to move the tube-grasping body along the tube-enlarging mandrel 2. Said tube-grasping body 3 is equipped with a plurality of tube-contacting parts 3f on which the slopes 3b are formed and slanted in the widening direction, toward the side of the opening 7b of the corresponding tube 7, and which are capable of radially expanding or axially compressing (the arrow E) in the cross direction of the longitudinal length of said hairpin tube 7. Said slope 3b is formed to reach the end-line 3o of the tube-contacting part 3f. Said tube-grasping body 3 is screwed and connected to the tube-grasping body holder 3l by the bolt 3k formed at the other side, the opposite side of said tube-contacting parts 3f. Said tube-grasping body holder 3l is capable of moving back and forth (the arrow F) by a sliding means such as a cylinder (not shown in the figure), in the longitudinal direction of the hairpin tube 7, within a prescribed pitch. Also, the guide-pipe 3c is screwed and connected to the guide-pipe holder 3d by the bolt 3h formed at the other side. Said guide-pipe holder 3d is capable of moving back and forth (the arrow G) by a sliding means such as a cylinder (not shown in the figure).
Four of said tube-contacting parts 3f of the tube-grasping body 3 are formed in the longitudinal direction of said tube-enlarging mandrel 2 to enclose the exterior circumferential surface of said tube-enlarging mandrel 2 (for example, if 6 is proper for a specific exterior diameter of the tube, then 6 or other number is set). Also, between the tube-contacting parts 3f, slits, each of which has a uniform length and a uniform separation width of a prescribed width 3u, are formed at four places (the quantity of such slits does not have to be 4 and is properly determined in proportion to the count of tube-contacting parts 3f). Through said slits, the diameter of each of the tube-contacting parts 3f is decreased in the axial direction of the tube-enlarging mandrel 2, as the guide-pipe 3c is advanced, by the guide-pipe holder 3d, toward the heat exchanger, in order to press and slide along the slope 3b which has been formed on the exterior surface of each of said tube-contacting parts 3f, and which is slanted in the widening direction toward the opening 7b of the corresponding tube 7. It is structured by a so-called collet chuck. The tube-grasping bodies 3 in their multitudes (not shown in the figure) with said plural tube-contacting parts 3f are installed along the surface of said component-loading platform 1c, in order to be faced with each of the opening 7b of hairpin tubes 7 being inserted into the heat exchanger 5.
4 is an enclosing-body shifting device comprising: a pair of enclosing-bodies 4a which is installed on said base platform 1b, and which is supported to rotate to enclose the hairpin part 7c of the hairpin tube 7 being inserted into the heat radiating fin 6 of said heat exchanger 5; a driving-cylinder 4e to drive to open or close said enclosing-body 4a; a base plane 4d with said driving-cylinder 4e and a pair of enclosing-bodies 4a; a guide rail 12 to slide said base plane 4d, to or from said component-loading 1c; and a round-trip cylinder 4f which enables said base plane 4d to move back and forth. Multiple quantity (not shown in the figure) of said pair of enclosing-bodies 4a are installed along the plane of said component-loading platform 1c, to be faced with each of the hairpin part 7c of hairpin tubes 7 which are inserted into the heat radiating fin 6 of the heat exchanger 5.
Explanation is given below about production of a heat exchanger 5, wherein a heat exchanger production apparatus 1 utilizes the tube-grasping body 3 configured as above, and the tube-enlarging mandrel 2 is inserted into the hairpin tube 7. First, as shown in FIG. 1, the heat exchanger 5 is installed on said component-loading platform 1c, and, subsequently, said heat exchanger 5 is pressed and fixed between the component-loading platform 1c and the pressing-plate 11, by lowering the pressing-plate 11 located above.
Next, the base plane 4d is advanced (not shown in the figure) along the guide rail 12, by operating the round-trip cylinder 4f of the enclosing-body shifting device 4. At the same time, the driving-cylinder 4e is operated, in order to enclose the hairpin part 7c of each of hairpin tubes 7, as indicated in FIG. 11, by the tongue shaped concavity 4g which resembles a tongue when viewed from the plane of a pair of enclosing-bodies 4a. Corresponding to said tongue shaped concavity 4g, a tongue shaped convexity 4c, which resembles a tongue when viewed from said plane, is formed on the interior surface of said tongue shaped concavity 4g. Said tongue shaped convexity 4c turns around the U-shaped interior circumferential surface of said hairpin part 7c in order to firmly stop the shrinkage of the hairpin tube 7 during the enlarging process.
Next, from the opening 7b of each of said hairpin tubes 7, as shown in FIG. 2(c), by inserting (the arrow A) each of the tube-enlarging mandrels 2 by a prescribed depth, the enlargement portion 7d with a prescribed length is formed. Subsequently, by advancing (the arrow B) the tube-grasping body 3, by the tube-grasping body holder 3l, from the opening 7b of the hairpin tube 7, toward the circumferential surface 7e of said enlargement portion 7d, the tube-grasping body 3 becomes connected to the exterior of said circumferential surface 7e, in the state where said circumferential surface 7e is surrounded by the tube-contacting parts 3f. 
Afterwards, if the guide-pipe 3c is moved (the arrow C), by the guide-pipe holder 3d, in the same direction of the movement of the tube-enlarging mandrel 2, the guide-pipe 3c presses the slope 3b while sliding along the same slope which has been formed on the exterior surface of each of said tube-contacting parts 3f, and which is slanted in the widening direction toward the opening 7b of the corresponding tube 7. Thus, the diameter of the tube-contacting parts 3f is reduced in the axial direction of the tube-enlarging mandrel 2, through the space isolation of the prescribed width 3u of the slits 3a. As a result, each of said tube-contacting parts 3f becomes to firmly grasp and support the circumferential surface 7e of the enlargement portion 7d of the hairpin tube 7.
Next, from this state, by moving said tube-enlarging mandrel 2 toward the hairpin part 7c of the hairpin tube 7, in order to support both of the hairpin part 7c and the opening 7b of the hairpin tube 7, it is possible to produce a heat exchanger, still keeping shrinkage of the entire length of hairpin tubes 7 at a minimum.
Also, when the tube-enlarging mandrel 2 is advanced toward the hairpin part 7c of the hairpin tube 7 while the circumferential surface 7e of the enlargement portion 7d is firmly grasped, as explained above, by plural tube-contacting parts 3f of the tube-grasping body 3, at the side of the opening 7b of the hairpin tube 7; the enclosing-body shifting device 4, equipped with the enclosing-bodies 4a capable of enclosing said hairpin part 7c, is moved back little (not shown in the figure) in the same direction of the movement of the tube-enlarging mandrel 2, in order to give some tensile strength for the entire hairpin tube 7. Thus, It is possible to produce a heat exchanger, keeping the shrinkage of the entire length of the hairpin tube 7 at a minimum, and considering the problem of shrinking of the entire length of the hairpin tube 7 during the enlarging process, as well as the problem of escaping of the hairpin tube 7 from the tube-contacting parts 3f and the enclosing-body 4a. As a result, it is possible to produce a heat exchanger, still keeping the material cost at a minimum.
Thus, it is possible to firmly grasp, by each of the tube-grasping bodies 3 having plural tube-contacting parts 3f, each of hairpin tubes 7 sitting at the interior side in the heat exchanger, as well as each of the tubes sitting at the exterior side in the heat exchanger, even for the following example cases: the case where hairpin tubes 7 are inserted into the heat radiating fin 6 of a heat exchanger 5 in a zigzag pattern (not shown in the figure); and the case where hairpin tubes 7 are inserted in a zigzag pattern, in multiple columns such as columns of 3, 4, or etc. (not shown in the figure) to decrease the gap (the insert pitch) between each of hairpin tubes 7.
Thus, since the tube-contacting parts 3f of said tube-grasping body 3 grasp the circumferential surface 7e of the enlargement portion 7d of the hairpin tube 7, by decreasing the diameter of the tube-contacting parts 3f in the axial direction, through the slits which are of a prescribed width 3u, and which are formed between each of the tube-contacting parts 3f, even for the case where the diameter of the hairpin tube 7 being enlarged is different according to the spec of the heat exchanger; it is possible to firmly and surely grasp the side of the opening 7b of the hairpin tube 7, by adjusting through the space distance of the slits 3a of a prescribed width 3u, between each of the tube-contacting parts 3f, even if there is little difference in each of diameters of the tubes. Also, as for the hairpin part 7c, since there is no need to replace the hook body 10 with another hook body having an almost identical circular arc to the interior circumference of the hairpin part 7c, in order to adapt to the different hairpin part 7c of hairpin tubes 7 with different diameters; and since it is possible to firmly and surely grasp by a pair of enclosing-bodies 4a, without altering the circular arc of the hairpin part 7c of the hairpin tube 7; it is possible to produce a heat exchanger, performing the enlarging process desired, without altering the heat exchanger production apparatus, even for the following cases: the case where the exterior diameter (the diameter of the tube, measured considering the circular arc) of the hairpin tube 7 being enlarged is different according to the spec of the heat exchanger 5, and the case where the entire length of hairpin tubes 7 is somewhat different.
Also, relating to the case where the hairpin part 7c of the hairpin tube 7 is firmly and surely enclosed by a pair of enclosing-bodies 4a as shown above, it is possible to exchange a pair of enclosing-bodies 4a to other type with a proper opening size, width, and length, according to the gap between insert tubes facing each other and the distance extruded from the terminal side of the heat radiating fin 6 of the hairpin part 7c of the hairpin 7; even for any of the following example cases:                the case where hairpin tubes 7 are inserted into a heat radiating fin 6 of a heat exchanger 5 in the same zigzag pattern (not shown in the figure) as above, and        the case where hairpin tubes 7 are inserted in a zigzag pattern, in multiple columns (not shown in the figure) such as columns of 3, 4, or etc. to decrease the gap between each of hairpin tubes (the insert pitch).However, unlike the hook body 10 of the prior art, since the hairpin part is enclosed by a pair of enclosing-bodies 4a, there exists some permissible range and it is thus possible to avoid frequent change of the hook body 10. However, the most important point is the fact that it is possible to firmly fix the hairpin part 7c of each of the hairpin tubes 7 sitting at the interior side in the heat exchanger, as well as the hairpin part 7c of each of the hairpin tubes sitting at the exterior side in the heat exchanger, by allocating a pair of enclosing bodies 4a to each of the hairpin parts 7c.         
Also, even if insert tubes 7 of other types than the hairpin tube are inserted, for example, if multiple straight tubes (not shown in the figure) are inserted, it is possible to produce a high quality heat exchanger with high precision, by enclosing and supporting, by a pair of the enclosing-bodies 4a, an end of the straight tube extruding from the terminal side of the heat radiating fin 6, and by inserting the tube-enlarging mandrel 2 into the opening 7b of the other end of the straight tube, by the same procedure as shown above.
Therefore, even for the case where insert tubes are inserted into a heat radiating fin, in multiple columns such as columns of 3, 4, or etc. to decrease the gap between insert tubes, and the case where the diameter of insert tubes being enlarged is different according to the spec of the heat exchanger, it is possible to firmly grasp and perform the enlarging process for insert tubes sitting at the interior side in the heat exchanger, as well as the tubes sitting at the exterior side in the heat exchanger. As a result, it is possible to produce a high quality heat exchanger, still keeping the material cost at a minimum by maintaining shrinkage of total length of insert tubes at a minimum.
Also, as shown in FIG. 2(d), if a bump 3e is formed at each of the tube-contacting parts 3f for pressing (the arrow D) the circumferential surface 7e of said enlargement portion 7d, at the position where each of the tube-contacting parts meets the enlargement portion 7d of the hairpin tube 7, in order to build up the extruded-part 7g extruding from the interior circumferential surface 7f of said hairpin 7, in the axial direction of the tube-enlarging mandrel 2; it is possible to surely set the reference location of the opening 7b during the enlargement process, and therefore, it is possible to produce a high precision heat exchanger by the enlarging process with higher precision.
On the other hand, the method, which is very similar to the Japanese Patent 10-85878, and which still considers the situation explained in FIG. 2(d) above, is Japanese Patent 9-99334 wherein a slope is formed in front of the bump which is formed at each of the tube-contacting parts, in order to prevent said opening from being deformed by a collision with the opening; a slope is formed in front of the guide pipe, for reducing the sliding abrasion against the slope on the exterior surface of each of said tube-contacting parts; a bolt is formed on the exterior circumferential surface of the tube-contacting part, a nut is formed on the interior circumferential surface of the guide-pipe, and said guide-pipe is screwed by said bolt and nut and installed for moving said guide-pipe back and forth.